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Education

Research Fields

Electronic structure studies of materials

Structure and properties of atomic clusters

Current Research Projects

In many materials, the nature of the atomic bonding does not follow simple, well-established chemical rules. For example, the regular arrangement of the atoms in a crystal is broken by the presence of a surface. In most cases, the atoms at the surface relax away from their “ideal” positions and this “reconstruction” can have important implications for surface properties. In a similar way, the bonding in atomic clusters, small collections containing tens to hundreds of atoms, is generally quite different from the ideal bonding represented in bulk solids. Clusters can be thought of as being made up of atoms that are either on or very near to the cluster surface. The properties of clusters are therefore very different from those of corresponding bulk solids and can be very sensitive to cluster size. In our research, we use accurate, first-principles electronic structure methods (density functional theory) to investigate the structure and properties of atomic clusters. We have developed novel techniques for finding the optimal arrangements of the atoms in a cluster of given size. Much of our current work is devoted to investigating the dielectric response of clusters, e.g. what clusters can be thought of as “metallic” and what can be thought of as insulating or semiconducting? Our calculations make use of a large cluster of workstations at CMU. Funding for our work comes from NSF, DoE, and CMU.